Spot the false statement?
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Answer: C. Thermal conductance of a wall of thickness ‘L’, thermal conductivity ‘k’ and heat flow area ‘A’ is kL/A
Explanation
Thermal conductance for a flat wall is given by thermal conductivity times area divided by thickness. Stating conductance as conductivity times thickness divided by area inverts the correct physical relationship. Dimensional analysis proves that thermal conductance must increase with area and decrease with wall thickness. Thermal conductance represents the inverse of thermal resistance for a specific conduction heat transfer path. Conductance units are expressed in watts per kelvin, reflecting heat flow rate per unit temperature difference. Fourier law provides the mathematical foundation linking material conductivity, area, and thickness to conductance.
Building insulation and furnace wall designs rely on accurate thermal conductance calculations to limit heat loss. Electrical and thermal circuit analogies depend on correct inverse relationships between resistance and conductance. Thermal engineering standards require precise formulation of material conductances for energy audits. Reciprocal of thermal resistance is correctly defined as thermal conductance in standard heat transfer terminology. Unit of thermal conductance is indeed watts per kelvin in the International System of Units. None of these options is correct because one of the listed choices contains a deliberate formula error.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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